1. Field of the Invention
The present invention pertains to surgical cutting instruments and, more particularly, to surgical cutting instruments having an elongated inner cutting member rotating about its axis within an elongated outer tubular member having a cutting window at its distal end which cooperates with the inner member to cut or resect bodily tissue, the cut tissue being aspirated through the inner member.
2. Description of the Prior Art
The use of elongated surgical cutting instruments has become well accepted in performing closed surgery such as arthroscopic or, more generally, endoscopic surgery. In closed surgery, access to the surgical site is gained via one or more portals, and instruments used in the surgical procedure must be elongated to permit the distal ends of the instruments to reach the surgical site. Surgical cutting instruments for use in closed surgery--also known as "shavers"--conventionally have a straight, elongated outer tubular member terminating at a distal end having an opening in the end or side wall (or both) to form a cutting port or window and a straight, elongated inner tubular member concentrically disposed in the outer tubular member and having a distal end disposed adjacent the opening in the distal end of the outer tubular member. The distal end of the inner tubular member has a surface or edge for engaging tissue via the opening in the distal end of the outer tubular member and in many cases (but not all) cooperates with the opening to shear, cut or trim tissue. In some cases, such as burrs, the opening in the outer tube merely allows access to the tissue and does not otherwise cooperate with the window. The inner tubular member is rotatably driven about its axis from its proximal end, normally via a handpiece having a small electric motor which is controlled by finger actuated switches on the handpiece, a foot switch or switches on a console supplying power to the handpiece. The distal end of the inner tubular member can have various configurations depending upon the surgical procedure to be performed, and the opening in the distal end of the outer tubular member has a configuration to cooperate with the particular configuration of the distal end of the inner tubular member. For example, the inner and outer tubular members can be configured to produce whisker cutting, synovial resection, arthroplasty burring or abrading, side cutting, meniscus cutting, trimming, full radius resection, end cutting and the like, and the various configurations are referred to generically as cutting blades or edges. Cut tissue is aspirated through the hollow lumen of the inner tubular member to be collected via a vacuum tube communicating with the handpiece.
The aforementioned elongated surgical cutting instruments have also been produced in angled configurations in which the distal tips of the inner and outer members are aligned and offset or bent at a fixed angle from the proximal ends of the aligned inner and outer members. Examples of such fixed-angle rotary surgical instruments are shown in U.S. Pat. No. 4,646,738 (Trott), assigned to the assignee hereof, and in European Patent Application 0 445 918 (Krause et al). In other respects the operation of these fixed-angle shavers is largely the same as that of the straight shavers described above.
Each of the fixed-angle rotary surgical instruments necessarily has the window in the outer member oriented in a fixed position relative to the offset angle. While various fixed-angle instruments may be manufactured, each with a given offset angle and/or with a given window orientation, each instrument necessarily requires that the window be in a fixed position. It has been found that the position of the window would in some instances be better positioned at an orientation different from that normally produced. Obviously manufacturing numerous fixed-angle outer tubes with windows in varying positions would create tremendous inventory problems for users and manufacturers alike. There is a need for an angled shaver system in which the orientation of the cutting window in the outer tube may be easily varied without the need to carry excessive inventory.
Known fixed-angle shavers are produced with only one offset angle--generally 10.degree. to 15.degree.. There is a need for a variety of offset angles in addition to those which are normally produced. Even if a variety of offset angles were produced the user or manufacturer would need to carry a large inventory for varying surgical indications. There is a need for an angled shaver system in which a variety of offset angles could be incorporated into angled shavers.
It is accordingly an object of this invention to produce a rotary surgical cutting instrument in which the offset angle is variable.
It is an additional object of this invention to produce a rotary surgical shaver in which the offset angle is selectable by a user.
It is also an object of this invention to produce a rotary surgical shaver in which the cutting window at the distal tip of the instrument may be oriented in any direction selected by a user.
It is an additional object of this invention to produce a rotary shaver in which the orientation of the cutting window may be combined with any one of several selected offset angles to produce a unique instrument from a single, base system so that a large inventory of product need not be carried.
It is yet another object of this invention to produce a tool for assisting in the creation of uniquely angled rotary shavers.
It is still another object of this invention to produce a system in which a user may create a unique rotary shaver, angled as desired.
It is still another object of this invention to produce a surgical shaver system in which angled shavers may be created from a minimum number of parts.
It is also an object of this invention to produce a surgical shaver system in which variable angle shavers may be created by users and in which the selected angle will be maintained during normal use of the shaver, although another angle may subsequently be created from the same, previously bent shaver.